Systems and devices for achieving high throughput attachment and sub-micron alignment of components

ABSTRACT

Systems and devices for achieving high throughput attachment of sub-micron alignment of components are provided. One such device can include a fixture for holding a chuck, the fixture including a plurality of alignment features for adjusting a position of the chuck, the chuck includes a top layer including a vacuum aperture for holding a first component and a bottom layer made from a translucent material, wherein the bottom layer is directly attached to the top layer.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to and the benefit of U.S. ProvisionalApplication No. 62/069,635 filed on Oct. 28, 2014, entitled, “LASERDIODE AND SUBMOUNT ASSEMBLY CHUCK WITH SILICON CARBIDE, SAPPHIRE, ANDPLASTIC SHIM”, the entire content of which is incorporated herein byreference.

BACKGROUND

Heat assisted magnetic recording (HAMR) technology for use in a datastorage device involves use of a laser heating source to provideadditional energy during the data writing process (e.g., as data iswritten to a magnetic media disk). The energy/heat source is typicallyimplemented using a semiconductor laser diode chip bonded on a sub-mountchip which, when the laser diode and sub-mount are considered togetherafter bonding, is referred to as a Chip-On-Sub-mount-Assembly or COSA.The COSA is then attached to a magnetic head slider and the light energyfrom the laser diode chip is guided to the air bearing surface of theslider through a waveguide disposed in the slider to heat up themagnetic media for writing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate a perspective and expanded views of a chuckused for component bonding according to one embodiment.

FIGS. 3 and 4 illustrate a perspective and expanded views of anotherchuck used for component bonding according to one embodiment.

FIGS. 5a and 5b illustrate a side view of a component bonding fixtureaccording to one embodiment.

FIG. 6 illustrates a side view of another component bonding fixtureincluding an absorption layer according to one embodiment.

FIG. 7 illustrates a sequence of front views of a system and process forbonding components according to one embodiment.

DETAILED DESCRIPTION

Some embodiments include systems and devices for achieving highthroughput attachment and sub-micron alignment of components. Oneexample of a system and device to achieve this is in regard the assemblyof components for COSA and COSA to slider bonding process. The COSA andCOSA to slider bonding process both involve a high accuracy typealignment and bonding, which is preferably accurate to submicron levelsor better. The bonding process itself can involve a eutectic or epoxytype attachment. The high accuracy bonding is needed to ensure that theoutput of a semiconductor laser diode chip (e.g. production laser, laserdiode, HAMR laser, second component) is aligned to the entry point ofthe waveguide in the slider, and to thereby ensure that maximum lightenergy is transferred from the laser to the waveguide in the slider. Thealignment accuracy determines the amount of energy channeled into thewaveguide and therefore an efficiency of the assembly as a whole. Whenthe alignment is poor, more energy is needed from the laser diode toensure sufficient energy is channeled through the waveguide to heat themedia. Thus, poor alignment leads to low energy efficiency and higherthan needed light energy. Accordingly, systems and methods for achievinghigh throughput attachment and accurate alignment of components for HAMRare needed.

COSA production of HAMR requires a COSA bonding process which appliesthe laser energy through a chuck to heat up a submount (e.g. secondcomponent) to melt a bonding material (e.g. solder) positioned between alaser diode and a submount to bond the laser diode and submount. Thissystem and process will be further described below in relation to FIG.7.

FIGS. 1 and 2 illustrate a perspective and expanded views of a chuckused for component bonding according to one embodiment. The chuck 100can include a top layer 102, where the top layer 102 can be made of amaterial having one or more of the following characteristics: sufficientthermal conductivity, high temperature strength, and low displacementmaterial. High thermal conductivity, for example, can be between 50 to200 W/(m·K). High temperature strength, for example, can have a specificheat between 600 to 800 J/(kg·K). Low displacement material, forexample, can have a coefficient of linear thermal expansion between40-800° C. less than 5×10⁻⁶/° C. One example of material used for thetop layer 102 is silicon carbide. The top layer 102 can have a thicknessbetween 0.8-1.2 mm.

The chuck can include a bottom layer 104 connected to the first layer102. The bottom layer 104 can be made of material having one or more ofthe following characteristics: transparent, high temperature strength,low thermal expansion, and high compressive strength. Transparentmaterial, for example, can be a material that has a percenttransmittance more than 95% for 500 nm to 1500 nm wavelength laser. Hightemperature strength, for example, can have a specific heat between 600to 800 J/(kg·K). Low thermal expansion, for example, can have acoefficient of linear thermal expansion between 40-800° C. less than6×10⁻⁶/° C. And, high compressive strength material, for example, can bea material having a compressive strength between 2,000 to 3,000 MPa. Oneexample of material that can be used for bottom layer 104 is glasssapphire. The bottom layer 104 can have a thickness between 0.3-1.0 mm.

Chuck 100 can also include vacuum nozzle 106, vacuum cavity 108, andvacuum hole 109 to retain a first component (reference numeral 142 inFIG. 7) on the chuck top layer 102 during component attachment. Vacuumnozzle 106 can be attached to bottom layer 104 and in fluidcommunication with vacuum cavity 108 formed in top layer 102. Top layer102 can also include vacuum hole 109 in fluid communication with vacuumcavity 108. The vacuum hole 109 can be configured to facilitate a vacuumpressure on the first component.

Chuck 100 can also include fastener assembly 110. Fastener assembly 110can include a plurality of fasteners meant for attaching the top layer102 and bottom layer 104, and further for securing the vacuum nozzle 106to the chuck 100. A fastener (as used in this detailed description) caninclude, but is not limited to, any combination of nut, bolt, stud,weldment, washer, rivet, nail, screw, or the like. One skilled in theart can appreciate that vacuum nozzle 106, vacuum cavity 108 and vacuumhole 109 can be modified in structure and location in chuck 100 toachieve the goal of securing a component to chuck 100.

FIGS. 3 and 4 illustrate a perspective and expanded views of anotherchuck 100′ used for component bonding according to one embodiment. Chuck100′ is similar to chuck 100, and therefore common features that havethe same reference numeral will not be described. Chuck 100′ can includea top layer 102 that has a first layer 102 a and second layer 102 b.Second layer 102 b can be positioned between first layer 102 a andbottom layer 104. First layer 102 a can be made of material having oneor more of the following characteristics: low thermal conductivity, lowtemperature strength, and has a high thermal expansion. Low thermalconductivity, for example, can be between 2 to 5 W/(m·K). Lowtemperature strength material, for example, can have a specific heatbetween 460 to 480 J/(kg·K). A low coefficient of thermal expansion, forexample, can be between 40-800° C. less than 12×10⁻⁶/° C. One example ofmaterial that can be used for first layer 102 a is zirconia. First layer102 a can have a thickness between 0.3-0.7 mm.

Second layer 102 b can be made of material having one or more of thefollowing characteristics: low thermal conductivity, high temperaturestrength, and low displacement material. Low thermal conductivitymaterial, for example, can be between 1.3-1.5 W/(m·° C.). Hightemperature strength material, for example, can be a specific heatbetween 0.6-0.85 J/(kg·° C.). Low displacement material, for example,can have a coefficient of linear thermal expansion between 25-800° C.less than 123×10⁻⁷/° C. The thickness of second layer 102 b can bebetween 0.3-0.7 mm. One example of material that can be used for firstlayer 102 b is machinable ceramic glass. Further, the vacuum hole 109can extend through second layer 102 b.

FIGS. 5a and 5b illustrate a side view of component bonding fixture 132according to one embodiment. Component bonding fixture 132 can include achuck housing 130, chuck 100/100′, and alignment features 120, 122, and124. The chuck housing 130 can be made of aluminum or stainless steel,and can be structured to substantially contain chuck 100/100′ except forportions of chuck 100 that are proximate to an assembly heating element(e.g., an assembly laser, a conductive heating device, a microwaveheating device, an ultraviolet light heating device) 148 (see FIG. 7)and areas where the first and second component are placed on the chuck100/100′ (see FIG. 7). The component bonding fixture 132 can alsoinclude alignment features 120, 122, and 124, which function to finelyposition chuck 100/100′. Alignment feature 120 (e.g. or top levelfastener), can contact one or more locations of the chuck top layer 102.By adjusting the alignment feature 120, the alignment feature 120 cancontact and alter the position of the chuck 100/100′. Alignment features122 (e.g. leveling ball) and 124 (e.g. side leveling fastener), cancontact various locations of the chuck bottom layer 104. By adjustingthe alignment feature 124, the alignment feature 124 will contact thealignment feature 122, which will contact and alter the position ofchuck 100/100′.

FIG. 6 illustrates a side view of component bonding fixture 132′, whichincludes a stress absorption layer 126 according to one embodiment.Component bonding fixture 132′ is similar to component bonding fixture132, and therefore common features that have the same reference numeralwill not be described. The stress absorption layer 126 can be made of ahigh quality plastic material that can reduce compression (less than0.15% displacement at 500 psi compressions) from alignment features 120and 122. The thickness of the stress absorption layer can beapproximately between 0.010-0.012 inches. The stress absorption layer126 can be positioned between the alignment feature 120 and the chucktop layer 102. Further, the stress absorption layer 126 can bepositioned between the alignment feature 122 and the chuck bottom layer104. Stress absorption layer 126 can be structured to have a length longenough to extend to a position between the alignment feature 120,alignment feature 122, and chuck 100/100′ in order to reduce stressimposed by those components on chuck 100/100′. Component bonding fixture132′ can include one or more stress absorption layers 126 withoutdeparting from the scope of the disclosure.

FIG. 7 illustrates one example of a sequence of front views of a system140 and process for bonding components, using component bonding fixture132/132′ and chuck 100/100′ according to one embodiment. This system 140has been simplified for the purposes of illustrating one use ofcomponent bonding fixture 132/132′ and chuck 100/100′. The system forbonding components 140 can include a pick up tool 146, component bondingfixture 132/132′ and assembly heating element 148 (for bonding a firstcomponent 142 to a second component 144). First, in Step 1, the pick uptool 146 picks up the first component and places it on bonding fixture132/132, preferably on the vacuum hole 109 (not shown). Prior to thepick up tool releasing the first component 142, the vacuum nozzle 106 isturned on creating a suction force at vacuum hole 109 in order to securethe first component 142 to chuck 100/100′. Next, in Step 2, the pick uptool 146 picks up the second component 144 and places it on the firstcomponent 142. The pick up tool 146 pushes the second component 144 downonto the first component 142 with a sufficient amount of force to ensureproper bonding in the Step 3. In Step 3, the assembly heating element148 is turned on to deliver heat energy 149 through chuck 100/100′ tothe first component 142. The heat energy 149 is transferred through thefirst component 142 to activate a bonding material between the firstcomponent 142 and second component 144. In Step 4, after the bonding offirst component 142 and second component 144 is finished, the pick uptool 146 moves the finished assembly to another staging area.

As mentioned above, system 140 has been simplified for illustrationpurposes. Those skilled in the art will appreciate that system 140 caninclude various sensors and processors to enable the system to properlywork to ensure high throughput and sub-micron alignment. For example, inStep 2, in order to properly align the first component 142 and secondcomponent 144, the system can include a vision or sensor system toenable sub-micron alignment of the components in relation to each other.For example, components can be brought close together using a distancesensor. The distance sensor can scan across the bottom surface of thefirst component 142 and the bottom surface of the second component 144to determine a relative distance or offset between them. The relativeoffset between the components can be measured by the distance sensor andcorrected by one or both the pick up tool 146 and chuck 100/100′ until adesired alignment is achieved. After a sufficient alignment is achieved,the second component 144 can be brought toward the first component 142.Further, in Step 3, the system 140 can include a force control sensorwhich is configured to sense a contact force between the first component142 and second component 144.

In one embodiment, the alignment process of Step 2 can be thought of asa passive alignment stage. In other embodiments, the process can useactive alignment to align the components prior to bonding. In oneexample, a waveguide configured to receive light and a sensor coupled tothe waveguide can be used for alignment. More specifically, the sensorcan provide information indicative of an amount of light received by thewaveguide of the slider.

In one embodiment, the process can perform the sequence of actions in adifferent order. In another embodiment, the process can skip one or moreof the actions. In other embodiments, one or more of the actions areperformed simultaneously. In some embodiments, additional actions can beperformed.

A processor can be coupled electrically to the first component 142, thesecond component 144, the assembly heat element 148, the pick up tool146, a force control sensor, a distance sensor, and a high resolutioncamera. The processor can be coupled to other components as well. Theprocessor can be coupled to the vacuum nozzle 106 and configured tocontinuously apply a vacuum pressure to the chuck 100/100′ to hold thefirst component 142, during such vacuum pressure application, to aid inalignment of the first component 142 and second component 144. Aprocessor can also be coupled to the pick up tool 146 to bring the firstcomponent 142 and second component 144 into contact. Further, aprocessor can be coupled to assembly heat element 148, to control laserpower during the bonding process. In several embodiments, such aprocessor can effectively execute some or all of the aforementionedoperational steps of the system 140 of FIG. 7.

In this context, the processor refers to any machine or selection oflogic that is capable of executing a sequence of instructions and shouldbe taken to include, but not limited to, general purposemicroprocessors, special purpose microprocessors, central processingunits (CPUs), digital signal processors (DSPs), application specificintegrated circuits (ASICs), signal processors, microcontrollers, andother suitable circuitry. Further, it should be appreciated that theterm processor, microprocessor, circuitry, controller, and other suchterms, refer to any type of logic or circuitry capable of executinglogic, commands, instructions, software, firmware, functionality, orother such information. In some embodiments, a processor may be acomputer.

The aforementioned description can be used in the bonding of componentsof a HAMR slider. For example, a sub-mount (first component 142) can bebonded to a HAMR laser (second component 144), to form a COSA. Further,the aforementioned description can be used in bonding a COSA (firstcomponent 142) to slider (second component 144) to form a HAMR slider.This can significantly reduce the machine cost by performing two bondingprocesses with one equipment set.

In several embodiments, the HAMR slider is can be useful for use withina hard disk drive to effect heat assisted magnetic recording. In otherembodiments, the bonding of components can be suited for otherapplications (e.g., other micro-scale semiconductor chip applicationsinvolving use of a laser).

Both chuck 100 and 100′ were tested and found to have performed superiorin specific metrics related to the system bonding process. For example,the use of a bottom layer 104 having translucent properties enabled thechuck 100/100′ to perform bonding process with lower laser power forlonger time without significant degradation of the chuck 100/100′.Further, use of top layer 102 material as described above resulted in amore robust chuck 100/100′. For example, there was less damage to thevacuum hole 109, thus increasing the alignment accuracy (e.g.,maintaining position of first component or centering sigma).

While the above description contains many specific embodiments of theinvention, these should not be construed as limitations on the scope ofthe invention, but rather as examples of specific embodiments thereof.Accordingly, the scope of the invention should be determined not by theembodiments illustrated, but by the appended claims and theirequivalents.

The various features and processes described above may be usedindependently of one another, or may be combined in various ways. Allpossible combinations and sub-combinations are intended to fall withinthe scope of this disclosure. In addition, certain method, event, stateor process blocks may be omitted in some implementations. The methodsand processes described herein are also not limited to any particularsequence, and the blocks or states relating thereto can be performed inother sequences that are appropriate. For example, described tasks orevents may be performed in an order other than that specificallydisclosed, or multiple may be combined in a single block or state. Theexample tasks or events may be performed in serial, in parallel, or insome other suitable manner. Tasks or events may be added to or removedfrom the disclosed example embodiments. The example systems andcomponents described herein may be configured differently thandescribed. For example, elements may be added to, removed from, orrearranged compared to the disclosed example embodiments.

What is claimed is:
 1. A device for bonding electrical components,comprising: a chuck including: a top layer including a vacuum hole forholding a component, and a bottom layer comprising a translucentmaterial, wherein the bottom layer is directly attached to the toplayer; and a fixture for holding the chuck, the fixture including aplurality of alignment features for adjusting a position of the chuck.2. The device of claim 1, wherein the top layer comprises siliconcarbide.
 3. The device of claim 1, wherein the translucent materialcomprises glass sapphire.
 4. The device of claim 1, further including afirst stress absorption layer positioned between at least one of theplurality of alignment features and the chuck.
 5. The device of claim 1,further including a first stress absorption layer positioned between thetop layer and at least one of the plurality of alignment features, and asecond stress absorption layer positioned between the bottom layer andat least one of the plurality of alignment features.
 6. The device ofclaim 1, wherein the top layer includes a first layer and a secondlayer.
 7. The device of claim 6, wherein the first layer of the toplayer comprises zirconia.
 8. The device of claim 7, wherein the secondlayer of the top layer comprises machinable glass ceramic.
 9. The deviceof claim 6, wherein the translucent material comprises glass sapphire.10. A device for bonding components, comprising: a chuck including: atop layer including a vacuum hole for holding an electrical component,and a bottom layer comprising a translucent material, wherein the bottomlayer is directly attached to the top layer; and a fixture for holdingthe chuck, the fixture including a plurality of alignment features foradjusting a position of the chuck; and a first stress absorption layerpositioned between the chuck and the fixture.
 11. The device of claim10, wherein the top layer comprises silicon carbide.
 12. The device ofclaim 10, wherein the bottom layer comprises glass sapphire.
 13. Thedevice of claim 10, wherein the first stress absorption layer ispositioned between the top layer of the chuck and the fixture, andwherein the device further comprises a second stress absorption layerthat is positioned between the bottom layer of the chuck and thefixture.
 14. The device of claim 10, wherein the top layer includes afirst layer and a second layer, the first layer of the top layercomprises zirconia, and the second layer of the top layer comprisesmachinable glass ceramic.
 15. The device of claim 14, wherein the bottomlayer comprises glass sapphire.
 16. The device of claim 1, wherein thetop layer is substantially parallel to the bottom layer.
 17. The deviceof claim 1, wherein the top layer and the bottom layer are eachsubstantially flat.
 18. The device of claim 1, wherein the top layercomprises a first material and the bottom layer comprises a secondmaterial different from the first material.